If a new version is coming, I would like to (re) suggest the following
* Adding an option for a file list when using srcgrid so we can put all the filenames in a text file , and use that file as a list without having to type filenames in the command line (ie: -filelist list.txt)
* Adding an automatic filename option to srcgrid, so that if we have a grid of X by Y, we can use filenameXxY and not have to list every single file for example let us say I will have a 3 by 2 grid, be able to name my files Myfile01x01, Myfile01x02, Myfile02x01, Myfile02x02, Myfile03x01, Myfile03x02, and then use an option like -filenameXxY Myfile. Or by default, if using srcgrid and giving only one name, the system would automatically assume the actual file names are built from this base name plus XxY (ie: -srcgrid 3 2 Myfile would look for the same names as described above)
* Cherry on the cake have the option to use -filenameYxX for when the filenames are generated with X and Y reversed
The just-released version of hdmake has a -srcgridfile option much like your -filelist above. We don't have automatic filename generation but you can write a little script to create the file list.